Reactive PVD-processes: Control is everything

Author: Dr. Joseph Brindley GENCOA and Dr. Anas Ghailane (AVALUXE) Reactive Magnetron SputteringReactive magnetron sputtering is a well-established PVD technique for depositing thin compound films on substrates. Common examples include: · Flat-panel displays for televisions and cell phones · Photovoltaic coatings on solar cells · Optical coatings · Decorative coatings on hardware and automotive components · Solar insulating coatings on architectural glass In reactive magnetron sputtering, sputtering of a target is conducted in the presence of a reactive gas (e.g., oxygen, nitrogen) that reacts with sputtered material and forms a compound film on the substrate. The most common reactively sputtered films are oxides and nitrides. What is the Challenge?The reaction between reactive gas and the sputtered material is known to cause process instabilities which means that the only stable operating area is in the presence of highly levels of reactive gas (excess gas). This leads to reduced deposition rates as the very high partial pressure of the reactive gas results in compound formation on the whole of the metal target surface (target poisoning). Sputter yields from poisoned targets are typically 3x to 5x less than from a metallic target.Solution: Reactive Gas ControllerA reactive gas controller as GENCOA’s Speedflo provides automatic feedback control and high-speed gas control to help prevent a runaway situation leading to target poisoning. With such a device it is possible to control a reactive process in what would usually be an unstable region. Gas control during reactive sputtering strongly influences the deposition rate and film properties of the compound being deposited. Reactive gases can trap the target in poisoned mode unless the partial pressures of the reactive gas(es) are individually monitored and controlled at high speed. The dynamics of a reactive sputtering system typically requires a closed-loop feedback speed of control in the 10’s of msec range. Active feedback control reacts and adjusts the reactive gas flow control valves within 1 msec. Depending upon gas line lengths and system size, the gas will then take typically between 10-100 msecs to enter the area in-front of the sputter target. With a closed loop feedback control time of 50 msec, so the closed loop control speeds are much longer. This slower response speed and CCD array drift means spectrometers are typically only used for process development rather than industrial process control. Many sputtering processes just use oxygen as the reactive gas, and hence another class of sensor comes into play – Lambda oxygen ‘sniffing’. Lambda sensors are used for automotive engine management to control the efficiency of the combustion. The lambda device converts the amount of group 16 gas present (in this case O2) into a proportional voltage output. With good control of the sensor temperature and adaption for use in a vacuum environment (see VacGasG16 type), this can be a convenient method to create a gas signal to use for successful reactive gas feedback control. Benefits of Reactive Gas Control · Much improved deposition rates are achieved (x 2.5 – 4 dependant on process*), for lower cost production · Thin film stoichiometry and properties control – eliminates process drift · More precisely controlled film uniformity, 1.5% over large areas (ideal uniformity for double low E glazing) · More energy efficient process (energy consumption can be reduced by up to 70%) – a typical customer was able to reduce power applied to each cathode by 100kW/h leading to >30% energy savings. For some applications, energy usage can be lowered by as much as 70% * Material properties of coated surface determines the maximum rate achievable, e.g., for architectural glass, too fast a deposition rate leads to a more metallic coating which can lead to future corrosion problems.

zum Artikel gehen

Intelligenter Mobilitätsassistent – smart EQ Control App

Elektrifizierende Neuigkeiten aus der Daimler Welt – für die neue Elektrotechnologie EQ bringt smart die smart EQ Control App. Die iOS und Android App bieten für den Nutzer den aktuellen Stand des Fahrzeuges sowie stellen verschiedene Funktionen online zu

zum Artikel gehen

Live Trances

So here are the last few live trances:21.06:Pet trance: Just another version of the pet trance Bunker trance. Its a bit different. Instead of walking down a nice staircase, you walk down deep into a bunker, sealed in my control and completely helpl

zum Artikel gehen

GSA Intelligent Control System v1.0.4

The program was developed for the event-oriented control of relay boards. With the programmed relays blinds, roller shutters, irrigation systems, solar systems, heating systems, etc. can be controlled. Changes since last release: - fixes

zum Artikel gehen

Control the color

A whole industry has grown up around PVD tool coatings because of the success of physical vapour deposition (PVD) technology over the past four decades. This industry is a result of the early pioneers in this field. A gas is delivered into the coating ch

zum Artikel gehen

Bestätigt: Universal Control für iPadOS verspätet sich

Apple hat beim diesjährigen iPhone-Event bestätigt, dass Universal Control nicht zum Start von iPadOS 15 verfügbar sein wird. Die Funktion soll eine bessere Zusammenarbeit mit dem Mac ermöglichen, doch der Start wird jetzt erst einmal verschoben.  (Weiter

zum Artikel gehen